Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances.
I don't necessarily agree with their agenda, but they are within their constitutional rights. The Constitution doesn't say anything about time parameters or allowed locations. And Lafayette Square is not White House grounds.
And keep in mind that we may end up being the aggrieved ones, come 20 January 2021. What then?